1.1 Diet and Exercise
- A balanced diet includes everything that is needed to keep the body healthy (TYPES OF FOOD) e.g. Mineral ions, vitamins, carbohydrates,fats and proteins.
- If someone's diet is unbalanced they can become malnourished.
- If you excercise, more energy is used by the body. Excercise increases the METABOLIC RATE which means that the chemicall reactions in cells work faster
- If the energy (food) taken in is less than the energy used the person will lose mass.
- The more excercise you do the more food you need.
- INHERITED factors also affect the metabolic rate.
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1.2 Weight Problems
- Eating too much food can lead to someone becoming OVERWEIGHT and OBESE.
- Long-term obesity can lead to severe health problems such as Type 2 DIABETES.(High Blood Preassure)
- Can be reduced by eating less carbohydrates and increasing the amount of excercise.
- Some people are unhealthy because they eat too little (STARVATION). These people might find it hard to walk and suffer from deficiency diseases due to lack of vitamins and minerals.
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1.3 Inheritance, exercise and health
- As said previously metabolic rate can be INHERITED from your parents.
- Two types of cholesterol good and bad.
- 'GOOD' CHOLESTEROL for your cell membranes and to make vital substances.
- A small amount of the population inherit 'BAD' CHOLESTEROL which can lead to HEART DISEASE.
- Foods rich in saturated fats can increase blood cholesterol levels.
- By exercising regularly a person can increase their metabolic rate and lower high cholesterol levels.
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1.4 Pathogens and disease
- PATHOGENS cause INFECTIOUS DISEASES.
- Pathogens are tiny MICROORGANISMS- ususally BACTERIA or VIRUSES.
- When bacteria or viruses enter the body they reproduce rapidly which makes us feel ill by producing TOXINS (poisons).
- Viruses are much smaller than bacteria and reproduce inside of cells. The damage to cells also makes you ill.
- SEMMELWEISS was the first to realise that infection could be transferred from person to person in a hospital. He told his staff to wash their hands between treating patients.
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1.5 Defence Mechanism
- The skin prevents pathogens getting into the body.
- Pathogens are also trapped by mucus and killed by stomach acid.
- WHITE BLOOD CELLS are part of the IMMUNE SYSTEM. They do 3 things to defend the body.
- INGEST pathogens (DIGEST and DESTROY)
- Produce ANTIBODIES to help destroy particular pathogens.
- Produce ANTITOXINS to get rid of the toxins that pathogens produce.
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1.6 Using drugs to treat disease
- ANTIBIOTICS kill infective bacteria in the body.
- Some medicines may relieve the symptoms but not kill the pathogens e.g painkillers.
- Viruses are difficult to kill because they reproduce in the body cells .
- Your immune system will usually overcome the ciral pathogen.
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1.7 Growing and investigating bacteria
- Bacteria can be grown on AGAR JELLY. It must be pure cultures of non-pathogenic (safe) bacteria.
- Uncontaminated culture of microorganisms can be used to find the effect of of antibiotics on bacteria.
- Contamination might come from your skin, the air, the soil or the water around you.
- If the culture becomes contaminated then other bacteria might grow this includes pathogens.
To grow microorganisms in a laboratory you must:
- Give them a jell containing nutrients- a culture medium (Agar jelly is used).
- Provide warmth+ oxygen.
- Keep them incubated at 25°C in school laboratories.
To keep the cultures PURE:
- Kill all the bacteria on the equipment
- Prevent microorganisms from air getting into the equipment
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1.8 Changing pathogens
- Some pathogens particularly viruses can MUTATE(change).
- Very few people are immune to these changed pathogens so diseases can spread quickly.
- Diseases that spread within the country result in an EPIDEMIC.
- Diseases that spread across countries result in a PANDEMIC.
- Some bacteria have developed resistance to antibiotics by natural selection. This is called MRSA which is the 'super bug'.
- Mutations of pathogens produce new strains which are resisitant to antibiotics.
- The resistant bacteria survive and reproduce. This is natural selection.
- Antibiotics should not be used for mild infections in order to prevent the rate of resisitant strains developing.
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- Dead or inactive forms of pathogens are used for VACCINES.
- The White Blood Cells react by producing ANTIBODIES.
- This makes the person IMMUNE. It prevents further infections because the body responds quickly by producing more antibodies.
- The antibodies recognise the ANTIGEN (protein shape) on the pathogen.
- The MMR vaccination (immunisation) is one of the several vaccines. This is given to prevent Measles, mumps and rubella.
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1.10 How do we deal with disease?
- Get vaccinated to prevent serious diseases.This protects individuals as well as society.
- Diseases such as measles can lead to long term damage to the body, such as deafness and occasionally death.
- Some vaccines cause side effects which may be mild or serious.
- Overuse of antibiotics can lead to the development of of new strains or bacteria.
- Doctors do not prescribe medicines for mild infections such as sore throats.
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